Driving me nuts, tested everything exactly how the factory says to check and it for code C2112 said the 4wd module was bad, bough one from the dodge dealer and installed it butt it still keeps setting a hard code C2112 for the front diff sensor circuit. I even went further and checked ohms and voltages both plugged in and unplugged and such with my same year truck that the 4x4 works perfect (for a stupid electric shift anyhow). I still get the service 4wd and no 4wd, every time I clear the code it is back on instantly. I bought the truck at auction and whoever owned it looks like they were chasing the same problem, it has a brand new t-case electric motor. It is a 2011 1500 5.7 hemi.